Step 1Roast the chiles: Heat the discada until hot. Roast the chiles until blistered and charred on all sides. Place in a plastic bag until cool enough to handle, then rub off the charred skin (do not wash, or this will remove flavor). Seed and coarsely chop the chiles, then set aside.
Step 2Heat the discada over medium-high heat until hot. Add the bacon and cook, stirring frequently, until the fat is rendered and the bacon begins to crisp, 6 to 8 minutes. Stir in the tomatillos, onions and garlic cloves. Cook, stirring frequently, until the vegetables are tender and the tomatillos begin releasing their juices, 8 to 10 minutes. Add the beer, scraping up any flavoring from the surface of the discada. Remove from heat.
Step 3Purée the vegetables, along with the chiles, cilantro and green onions in a food processor (this will probably need to be done in batches).
Step 4Season the tenderloin cubes with the salt and several grinds of pepper.
Step 5Heat the discada over medium-high heat until hot. Add the lard and brown the pork on all sides. Add the vegetable pure, along with the chicken broth. Reduce the heat to a gentle simmer and cook, stirring occasionally, until the pork is tender and the chili is thickened, 15 to 30 minutes. Remove from heat and serve.